The present invention relates to a bridging board used for connecting together two motherboards to obtain a single motherboard structure.
The constitution of an electronic device such as a computer in which a plurality of daughter board mounting slots are provided on a motherboard and a daughter board is mounted in each daughter board mounting slot is well known. In this case, the upper limit for the number of slots that can be provided on one motherboard is determined from the specifications of the computer configuration (for example a maximum of 8 slots). However, there are often demands to make it possible to use more daughter boards than this number set from the specifications, i.e. to increase the number of slots. A conventional method for answering to such demands is to provide a bridge circuit so that a number of slots beyond the above-mentioned upper limit can be installed.
A motherboard having a number of slots within the upper limit determined from the specifications always has a structure comprising a single system slot in which a system board is mounted and a plurality of daughter board mounting slots connected to the system slot via bus wiring; with only a single system slot, it is not possible for the above-mentioned upper limit to be exceeded. To construct a motherboard structure having a number of slots exceeding the above-mentioned upper limit, it is possible to use two motherboards each having a system slot, but there is then a problem that two system boards are required. A constitution of a single motherboard has thus been conceived in which a single downstream side (expansion side) system slot is provided in a section for additional expansion, and a plurality of downstream side daughter board mounting slots are connected to this downstream side system slot via downstream side bus wiring.
However, the motherboard thus constituted (the downstream side motherboard) is integrated with an upstream side motherboard so that the two function as a single motherboard, and hence the same functionality is obtained as when one of the upstream side daughter board mounting slots of the upstream side motherboard is connected to the system slot of the downstream side motherboard using a bridge circuit as described above and a system board is mounted in the downstream side system slot using an IC or the like provided in the bridge circuit.
If the bus wires connected to the connecting pins of the upstream side daughter board mounting slots have a non-parallel configuration, then a different type of signal is applied to each of the slots. In this case, it must be decided in advance which of the upstream side daughter board mounting slots to connect to the downstream side system slot using the bridge circuit, and connection of the non-parallel bus wires must be carried out accordingly.
When connection is carried out using a bridge circuit as described above, there is a problem that whenever the constituent upstream side and downstream side motherboards differ, the bridge circuit must be set correspondingly. Moreover, in actual practice, considering cost and product compatibility, there are often cases where one wants to directly connect two existing motherboards together to construct a single motherboard having an increased number of slots, and hence it is desirable to make it possible to meet such demands.
An object of the present invention is to provide a bridging board for connecting any two given motherboards together both physically and electrically to produce a structure that can be used as a single motherboard.
The bridging board of the present invention is for connecting an upstream side motherboard having an upstream side system slot and one or more upstream side daughter board mounting slots and a downstream side motherboard having at least a downstream side system slot. The bridging board has an upstream side connector fittable into any one of the upstream side daughter board mounting slots and a downstream side connector fittable into the downstream side system slot. The bridging board also has a plurality of bridge wires that electrically connect a plurality of wiring pins provided in the upstream side daughter board mounting slot and a plurality of wiring pins provided in the downstream side system slot when the upstream side connector is fitted into the upstream side daughter board mounting slot and the downstream side connector is fitted into the downstream side system slot, and IC switches that carry out connection changing on prescribed wires out of the plurality of bridge wires.
If a bridging board having such a constitution is used, then regardless of what kind of motherboards are used as the upstream side and downstream side motherboards, by connecting the motherboards together using the bridging board and then suitably setting the connection changing of the bus wires using the IC switches, it is possible to use the two motherboards as a single motherboard in which the two motherboards are integrated both mechanically and electrically. It is thus possible to connect any plurality of motherboards together using bridging boards according to the present invention, and hence construct a single motherboard having a large number of daughter board mounting slots.
Note that it is bus wires that have a non-parallel configuration in the upstream side and downstream side daughter board mounting slots for which connection changing is carried out using IC switches in this way. Moreover, the downstream side motherboard generally has at least one downstream side daughter board mounting slot in addition to the downstream side system slot, thus allowing a large number of daughter boards to be mounted.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.